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Soil or cement?

Many building components from foundation to final finish can be built by using soil-based ideas.

24bgp-greensensG9A1V8J9R3jpgjpgThe last week has been a week of messages in WhatsApp and elsewhere, claiming the highest recorded temperature for any inhabited parts of Earth has touched 60 degree C in Kuwait. We may not get any officially verified version of this possible rumour; it could be a fact or a figment of imagination and could even be a prank message just to amuse us.

Official records claim highest recorded temperatures to be above 56 degrees, as such this figure further moving up is not an impossibility considering the damage and distress we are causing to nature. However, imagining such high temperatures is a frightening proposition. So, what are we doing about it?

Many nations and institutions are addressing climate crisis; yet at the global scale they are yet to make a noticeable dent. If so, should we wait for something to happen through these major players or do our bit individually?

One area to work upon is simply to minimise the use of steel and cement.

Though considered as a boon to the construction industry, these two materials contribute much to resource consumption, energy demands, waste generation and heat production. The indoor and outdoor temperatures around their production plants are virtually uninhabitable.

Why cement?

Most owners and builders cannot imagine building without cement today. RCC is inevitable today, so as a part of it cement too. Yet, should the whole building – foundation, column, walls, lintels, chajjas, beams, stairs, roofs, plastering, waterproofing – be with cement and concrete? At least where possible, can they be with non-cement based material?

Many soil-based options can replace cement fully or in parts during building construction. Soil lends itself to adobe block, rammed earth, stabilised mud block, table moulded or wire cut bricks, jaali units, hollow clay block, clay filler and hourdi roof blocks, Mangalore tiles, water proofing tiles, flooring tile and many such other products.

Unbelievable but true, majority of building components from foundation to final finish can be built by using these soil-based ideas. Brick foundations are possible; jaali blocks make reinforced columns; hollow clay blocks are apt for walls and lintels; mud walls are a proven idea; tiles make attractive chajjas; RCC would have minimal steel and cement in filler roofs; hourdis can create both flat and curved roofs; arch panel and jack arches need only precast beams and clay flooring is among the best for the foot.

This listing may appear like pitching the opposites for a competition. Our media is full of discussions on herbal vs chemical shampoos; traditional vs modern dresses; local vs continental cuisine; made in India vs imported goods and many such others. Likewise, soil vs cement may sound like being part of these debates. However, the intention is not to place them as opposites, but be able to observe the appropriate and make a studied choice.

Today we need to choose not only with a concern for today, but equally with a concern for tomorrow.

HOUSE WITHOUT STEEL AND CEMENT

It has taken us only a few decades to wipe out traditional methods of building houses, but the clock can be reversed.

19bgp-greensens_19_2552825gWhen we look around our homes today, can we imagine that less than a hundred years ago we used to build without steel and cement, but today that appears impossible? Does it surprise us to realise it has taken us only a few decades to wipe out thousands-of-years-old methods of building houses? Strange but true, the rate at which we are shifting is both astonishing and alarming too.

In the wake of such a transformation, we also see scattered attempts to counter the change. The house of architect Dhruv Bhasker at Auroville is an apt example to prove how we can successfully reverse the clock, living in our times. At Auroville, for many decades alternative ideas have been explored and experimented; as such Dhruv’s house draws lessons from past experiences.

The foundation is built not with stones with cement mortar but using lime-stabilized mud rammed into the trench in layers. It is simple, practical and very economical, but if not done properly may lead to settlement cracks; hence should follow prescribed technicalities. Termites could be an issue, which is mitigated by using lime in critical areas.

Walls are made of local burnt bricks, plastered with hand-finished lime and sand mortar. Likewise, joints too use the same lime mortar, replacing the conventional cement mortar. However, larger part of the wall is made of rammed earth, left exposed or partly mud plastered. There are not too many lintels as per the design; the few that appear are done with single piece stone slab. Modern paints based on chemical pigments are totally avoided.

Locally available old doors and windows from demolished houses were re-used as they were and if not, by resizing them. Old wood needs to be carefully handled to take away the decomposed top layer and re-polished with durable finishes. Athangudi tiles, also called as Chettinad tiles, adorn the floors in vivid colours and hues, adding a rich pattern at places.

The roof is made with reused wood rafters and purlins, topped with country clay tiles, and the ceiling covered by wood boards.

Electricity power comes from solar photovoltaic panels, adequate for lighting, water pump and refrigerator, with a good quality inverter. Most of the roof rain water is harvested, diverted into an underground sump, filtered and then taken to the overhead tank.

Septic tanks and soak pits take care of the sewage.

Incidentally, it is not only a house without steel and cement, but also without any dependency on outside the site for water, sewage, and power. Presently, it is not a house for a large family, hence succeeds immensely as an alternative idea. Of course, there have been millions of such independent houses in our traditional villages, but majority do not support modern lifestyle.

The importance of such fresh thinking as seen in Auroville in general and Dhruv’s house in specific lies in finding ways to adapt local approaches for sustainable futuristic architecture.

BEWARE OF EXCESS CEMENT

Cement deteriorates with age, and has an inherent weakness of cracking.

28bgp-greensens_28_2355568gHow many of us know that India is the second largest manufacturer of cement in the world with more than 360 million tonne annual capacity? Is it a matter to be proud of? Majority will say, yes. The price of cement has come to indicate the health of market economy, shifting directions of monetary investments, rate of infrastructure development and such others. Again, an important information for all of us.

How many of us know that every tonne of cement produced causes nearly another tonne of carbon dioxide, a major contributor to greenhouse gases? Is it a matter to be proud of? This time hopefully, majority will say ‘no.’ This is besides the fact that cement also has very high embodied energy, a major concern today in sustainable buildings. If so, how should we treat this wonder material?

Cement is a product of calcium, aluminium, silicon and iron, supplied through mainly limestone, clay and sand. The mix in right proportion with more than 3/4th limestone is grinded, pre-heated and then heated up to 1400 degree centigrade in a rotating furnace kiln, where decarbonation takes place, releasing carbon dioxide, slurry and clinkers. The clinkers are set into a horizontal chamber for final and fine grinding.

Within about 200 years of its discovery, cement has conquered the world of construction, due to its versatility of usage, flexibility in design applications, strength and setting time.

While professionals may handle it more efficiently, even a village mason picks up the skills of working with cement very fast, hence its popularity. However, thanks to its popularity, we appear to be ignoring its drawbacks.

Though lime and cement share common raw material, cement deteriorates with age, while lime stays fit for long. Cement has an inherent weakness of cracking, passing on this trait to concrete too. As such, experts do not guarantee a cement and concrete building to last more than 60 to 80 years without periodic improvements.

Besides, it absorbs heat if directly exposed to sun, with surface cracks. If we checkout any building with only cement mortar plastering without wall paint, hundreds of cracks can be seen on the surface. Normal mortar tends to absorb water, being groscopic in nature, hence requires varied water-proofing applications. Traditional buildings in stone, wood, non-homogeneous roofs and such others could withstand minor settlement in site or even small-scale earthquakes. In contrast, cement as a material is not good to withstand settlements.

Despite knowing about the drawbacks of cement, we end up having cement mortar in all joints and surfaces; concrete in foundation, columns, lintels, beams, slabs, frames and coping bands; cement blocks in walls. What we are building today appears to be a cement building from head to toe.

While it is a dangerous trend in construction, it is equally a shame on us to neglect dozens of appropriate materials available to us. Once cement was a boon, today it may not be. It is time to look outside cement.

Myth of costs

We tend to ignore the environmental impact of using cement for all construction practices and do not consider alternatives

26bgp-green-sen_26_1631331gLet us try answering a simple question. Which item among the following list is the cheapest in terms of cost per kg. – old newspaper, cement, local vegetables or packaged mineral water? While most people may consider paper or vegetable, the surprise answer is cement. A bag of cement weighing 50 kg. comes at less than Rs. 350, hence costing less than Rs. 7 per kg., while even the old newspaper costs nothing less than Rs. 9 in Bangalore. Regarding vegetable prices, the less said the better.

Next, let us look at another question in continuation of the above. Among the above list of materials, which one consumes maximum energy and produces maximum wastage? Many of us may consider paper, but zero in on cement and we are right. Cement production consumes much and also wastes much.

Finally, third and last question in the series. Possibly which material contributes maximum to greenhouse gas emissions (GHG) and has the highest carbon footprint? Of course, now we all are sure of it being cement. The construction industry contributes to nearly one-third of all GHG emissions, within which four materials in heavy demand today, i.e. steel, cement, glass and aluminium, contribute majorly to greenhouse gases.

Contradiction

The foregone paragraphs are not meant to question and denounce cement, but use it as a case in point to discuss the myth of costs in eco-friendly approaches. A hidden contradiction in the contemporary sustainable discourses revolves around a possible belief that all that is cheap is sustainable in society and all that is costly is detrimental to nature. Considering the cost as a derivative of resource consumption, this theory may appear valid in certain cases. However, materials like cement being the backbone of the construction industry worldwide, it is produced in such large quantities, bringing the prices down, thanks to economies of scale.

When materials which are harmful to nature are available at such low prices, we tend to ignore the environmental impact of using them, for they are popular, seemingly necessary and available everywhere. Any alternative, possibly an eco-friendly one, comes at a higher cost, hence becomes less of a choice for all of us.

For sustainability

How is it possible for an energy intensive item, factory-made material, transported over long distances to cost so less, despite having high carbon footprint? Every material invented by humans depends upon nature to supply the raw sources and in turn produce the manufactured ones, causing a two-way impact – decreasing the natural and increasing the artificial. Yet, why do local and natural alternatives cost more than the artificial and manufactured? We may not be able to right away understand the complex market economics to get an easy answer, but need deep introspecting into such contradictions if we have to tread the path of long-term sustainability.

One thing is clear – during our times of green talk everywhere, economic cost and ecological cost are not directly related.